1. Field of the Invention
The present invention relates to manual winches with safe knockout tension release mechanisms, more particularly, the present invention relates to manual marine winches with a safety loading handle and integrated locking dog release.
2. Background Information
General Manual Marine Winches
Winches have been used in many applications. The present invention relates to manual winches which have been widely used in barges, tow boats and the like. Typically such a manual winch is attached to a boat deck and spools a towing cable or winch line on a rotating drum.
Manual winches remain in common use where a powered winch would be impractical or inefficient. In a manual winch the operator, through various mechanical advantages, can generate a very large tension on the winch line. Examples of manual winches are described in greater detail in U.S. Pat. No. 5,947,450 which is incorporated herein by reference. Examples of manual winches are sold by W. W. Patterson Company, Nabrico and Nashville Bridge Company. Other representative examples are found in U.S. Pat. Nos. 3,939,729; 4,106,754; 4,456,227; 4,566,674; 6,431,525; 6,572,083; 6,726,182; 6,938,881; 7,128,307; 7,179,852; 7,686,282, which are incorporated herein by reference.
A background summary of conventional winch design may be helpful to fully understand the scope and operation of the present invention.
The conventional prior art manual marine winch is described in U.S. Pat. No. 5,947,450 and includes a base plate and a pair of spaced side plates surrounding a rotatable spool or drum assembly. The rotatable spool assembly is rotationally supported between the side plates and includes a drum with a controlling gear. A control assembly is supported by the side plates and engages with the gear to rotate the drum for spooling of a cable (not shown) or wire rope or winch line thereon. The control assembly includes a hand wheel and an actuating lever or handle, also called a ratchet handle, each of which are used for manually operating the winch.
A foot brake may be attached to the side plate through which the control assembly extends. The foot brake, if provided, is adapted to frictionally engage the hand wheel. A swivel link may be attached to the base plate at a rear of the winch and pivotally attaches the winch to a D-ring of a boat deck or the like. The construction of the manual swivel winch may include the use of four tubular spacers for spacing the side plates apart. A bolt extends through the center of each spacer through aligned holes in the opposed side plates and is secured by nuts.
In a conventional marine winch a wire rope, the winch line, is spooled back and forth around the rotating drum and the winch line is subject to very large loads. The high loading can cause the outer layers of wire rope to become fouled, jammed or begin binding within the spaces between the lower level wire ropes. Further, rapid tension release in existing wire rope winch systems can result in what is known as “bird-nesting” of the spooled wire rope. This can make unwinding the winch very difficult in subsequent operation, and often requires a second deck hand to assist in the unwinding of the wire rope, or even the engine power of the tow boat. U.S. Pat. No. 7,543,800 which is incorporated herein by reference addressed some of these problems with the design and implementation of a “single stack” winch.
The conventional ratchet handle of the above describe marine winches will typically have a stowed position, generally the rearward position, in which it is disengaged from the gearing associated with the drum. The stowed position may have a stop secured to the sidewall or side plate acting as a rest for the handle and a visual indicator that the handle is in the stowed position. As the handle is rotated away from the stowed position it will engage the gearing associated with the drum to allow for tensioning of the drum and associated winch line, in a conventional fashion known in the art.
The tension is held on ratchet gears that are engaged with pawls or locking dogs. In conventional tensioning operation for the winch the pawls are engaged with the ratchet gears and the operator will rapidly wind up the winch line, and increase the tension, initially through the operation of the hand wheel. Once the tension reaches a relatively high amount on the winch line, the operator will continue the tensioning through the repeated use of the ratchet handle, often with the use of a handle extension or a “cheater bar” to add increased leverage. Once the final tension is achieved it is intended for the operator to move the handle to the disengaged or stowed position, typically the rearward position, to prepare the winch for tension release when desired.
A knockout lever, also known in the art, is used to disengage the pawls or dogs from the gears to release tension on the winch, when desired. When controlled payout is desired the footbrake, if provided, is engaged (or the hand wheel is gripped) and the knockout lever is utilized to disengage the pawls or dogs from the gears to allow for slow payout. Often the tension release is allowed to be somewhat rapid. The knockout lever is so named as it is often struck to be knocked out of engagement.
Dangerous Unintentional Handle Rotation with Knockout Operation of Conventional Manual Winch Designs
The manual tensioning handles of known marine winches should be disengaged to allow for safe unloading or payout of the winch line. If the tension is released on the drum through a knockout device with the handle still accidentally engaged, the handle naturally will rotate, through the gearing, with the drum. In such a case, with the drum under high loads or tension, the accidentally drum-engaged handle can be rotated quite fast and violently before striking a rear stop or the ship's deck. Aside to damaging the handles in this movement, of far greater concern is the potential injury to workers around the winch during such accidental winch handle movement.
The danger of unintended handle movement is only heightened if a handle extension, also called a cheater bar, is left on the handle that is left engaged with the gearing. A cheater bar is merely a length of pipe that operators have been known to add to the manual marine winch handle to increase the effective lever arm available to the operator for ease of tensioning the winch 10 or 50. Operators have broken arms and legs due to such undesired violent handle and cheater bar motion during knockout operation.
U.S. Patent Application Publication No. 2012-0068132, which is incorporated herein by reference, provides one solution to this handle problem with the design of a manual marine winch that includes a self releasing handle. The handle includes i) a ratchet gear coupled to the drum wherein rotation of the ratchet gear will cause rotation of the drum, ii) a rotating handle body with a manual end grip, iii) a user engaged trigger mechanism on the end grip moveable between an engaged position and a release position, and iv) a handle locking pawl on the handle body and coupled to the trigger mechanism and moveable between a position engaged with the ratchet gear rotationally securing the handle body to the ratchet gear and the drum when the trigger is in the engaged position and a position disengaged with the ratchet gear rotationally separating the handle body from the ratchet gear and the drum when the trigger is not in the engaged position. The self-releasing handle of U.S. Patent Application Publication No. 2012-0068132 represents a relatively complex handle and may not be adopted by all winch users.
U.S. Pat. No. 9,004,456 also addresses this issue and discloses a manual marine winch that includes a safety knockout override preventing release of winch tension without the handle in stowed position. The winch includes a housing; a rotating drum on the housing; a winch line on the drum; a control for spooling and un-spooling the winch line on the drum, wherein the control includes a handle for selectively tensioning the drum and moveable between a position engaged with the drum and a disengaged stowed position; a tension holding mechanism on the housing comprising a ratchet gear coupled to the drum, a pawl selectively engaged with the ratchet gear, and a knockout configures to selectively disengage the pawl from the gear to allow for release of winch tension; and a safety knockout override coupled to the housing and selectively engaged by the handle and configured to prevent release of winch tension when the handle is not in the stowed position. Thus there remains a need for preventing undesired handle movement during tension release on manual marine winches with the operation of a knockout device. The safety knockout override of U.S. Pat. No. 9,004,456 also represents a relatively complex design and thus may not be adopted by all winch users.
It is an object of the present invention to minimize the drawbacks of the existing manual winch handles and to provide a simple easy and safe marine winch.